title: Assessing near infrared optical properties of ceramic orthodontic brackets using cross-polarization optical coherence tomography.
abstract: Secondary decay (caries) under ceramic orthodontic brackets remains a significant dental problem and near infrared cross-polarization optical coherence tomography (CP-OCT) has the potential to detect underlying demineralization. The purpose of this study was to determine the effect of crystalline structure and chemical composition of ceramic brackets on CP-OCT imaging. Four ceramic brackets types, which were divided into monocrystalline and polycrystalline, were examined using CP-OCT. The results of this study demonstrated that the crystallinity of the ceramic brackets affected the 1310 nm CP-OCT imaging with the greatest attenuation seen in polycrystalline alumina brackets. The alumina polycrystalline bracket materials had significantly higher attenuation and scattering than alumina monocrystalline brackets (p < 0.05, ANOVA, Bonferroni). Additionally, bracket base morphology and composition affected NIR light attenuation. There was considerable attenuation in bracket bases that contained additive zirconium spheres (∼30 µm) and this alteration was significantly greater than the jagged alumina crystallographic alterations found in the other bracket systems (p < 0.05, ANOVA, Bonferroni). Noninvasive, near infrared (NIR) cross-polarization optical coherence tomography (CP-OCT) has potential to effectively image through portions of ceramic brackets; however, further investigation into the optical effects of resin integration in the base portion of the brackets is warranted.
authors.affiliation: Division of Pediatric Dentistry Department of Developmental and Surgical Sciences School of Dentistry, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Darren M
authors.initials: DM
authors.lastname: Isfeld
authors.forename: Conrado
authors.initials: C
authors.lastname: Aparicio
authors.forename: Robert S
authors.initials: RS
authors.lastname: Jones
mesh_terms: D000537:Aluminum Oxide; D002516:Ceramics / Q000737:chemistry*; D003460:Crystallization; D003799:Dental Stress Analysis; D007259:Infrared Rays; D008855:Microscopy, Electron, Scanning; D009967:Orthodontic Appliances; D019265:Spectroscopy, Near-Infrared; D041623:Tomography, Optical Coherence; D015040:Zirconium
chemical_list: D015040:Zirconium; D000537:Aluminum Oxide
keywords: dental caries; dental ceramics; imaging systems; medical optics instrumentation; optical coherence tomography; polarization